Vaginal aerobic bacterial flora was studied in 5 healthy bitches before, during, and after a 10-day period of treatment with ampicillin and an equally long period of treatment with trimethoprim-sulfamethoxazole. Blood variables and antimicrobial drug susceptibility also were studied. Bacteria were isolated from all bitches before the first treatment period. Bitches from which only a sparse number of bacteria were isolated had flora that varied from day to day. In most instances when bitches were given an antibiotic to which their vaginal bacterial flora was susceptible, these bacteria were eradicated after only 1 day of treatment. This was true for pasteurellae, streptococci, and, in all but one case, Escherichia coli. Staphylococcus intermedius was more difficult to eradicate, and, although susceptible in vitro, it was unaffected by antibiotic treatment in 1 bitch and it took 7 days to eradicate in another. Eradication of aerobic bacteria in the vagina was total only in the bitch that had sparse flora from the beginning. Bacteria colonized within 0 (in 4/5 bitches) to 4 days after termination of treatment with ampicillin and within 0 (in 4/5 bitches) to 3 days for trimethoprim-sulfamethoxazole. Mycoplasmas emerged during and after both treatment periods, and E coli became apparent during treatment with trimethoprim-sulfamethoxazole. Because mycoplasmas may be genital pathogens in bitches and E coli is a common uropathogen, their appearance should be an argument against widespread use of antibiotics in healthy breeding bitches. Two bitches developed a vaginal discharge during treatment or shortly after. Blood variables did not change during the study, nor did antimicrobial drug resistance of the isolated bacteria.

The in vitro antimicrobial activities of aditoprim (AP), a new dihydrofolate reductase (DHFR) inhibitor, trimethoprim (TMP), sulfadimethoxine (SDM), sulfamethoxazole (SMX), and combinations of these drugs against some porcine respiratory tract pathogens were determined by use of an agar dilution method. The minimal inhibitory concentrations (MIC) of these agents were determined twice against Bordetella bronchiseptica (n = 10), Pasteurella multocida (n = 10), and Actinobacillus pleuropneumoniae (n = 20) strains isolated from pigs suffering from atrophic rhinitis or pleuropneumonia. All B bronchiseptica strains were resistant to AP and TMP. The MIC50 values of AP and TMP for P multocida were 0.25 and 0.06 microgram/ml, respectively, and for A pleuropneumoniae, 1 and 0.25 microgram/ml, respectively. The MIC50, values of SDM and SDM for B bronchiseptica were 4 and 1 microgram/ml, respectively; for P multocida, 16 and 8 microgram/ml, respectively; and for A pleuropneumoniae, 16 and 8 microgram/ml, respectively. The investigated combinations of the DHFR inhibitors and the selected sulfonamides had synergism for the A pleuropneumoniae strains; the MIC90 values of the combinations were less than or equal to 0.06 microgram/ml. Potentiation was not observed for the B bronchiseptica and the P multocida isolates. The MIC of the combinations against B bronchiseptica and P multocida corresponded respectively to the concentrations of the sulfonamides and the DHFR inhibitors in the combinations. For A pleuropneumoniae, 2 types of strains were used (25% of serotype 2 and 75% of serotype 9). Type-2 strains had lower susceptibility than type-9 strains to AP and TMP as well as to SDM and SMX (at least a fourfold difference in MIC between the 2 types of strains). The MIC of the combinations were similar for the 2 types of strains.

Plasma elimination rates of sulfamethazine (100 mg/kg of body weight, IV), trimethoprim (20 mg/kg, IV), and antipyrine (35 mg/kg, IV) were studied in adult female dwarf goats (n = 5) before and after implantation with trenbolone acetate (5 mg/kg). Pretreatment with trenbolone caused a significant decrease in the elimination rate of the drugs tested: for sulfamethazine, 5 times; for antipyrine, 3 times; and for trimethoprim, 2 times. After treatment with testosterone (1 mg/kg, SC, twice weekly for 2.5 weeks), female goats (n = 5) had a similar decrease in the elimination rate of sulfamethazine. Other induced effects included a change in social behavior, a lower voice, and the development of a typical billy goat-like odor. Plasma creatinine concentrations after androgen administration were significantly higher than those before androgen administration; changes were not observed in plasma urea values. Because of the differences observed, we believe that more attention should be paid to the effects of androgenic agents on drug kinetic properties, with particular reference to studies on clinical efficacy, side effects, and drug residues in food products.

The article presents a rapid and simple analytical procedure for determination of four sulfonamides (sulfadiazine, sulfamerazine, sulfamethazine and sulfamethoxazole), trimethoprim, tylosin and amoxicillin in animal medicated feed.

The aim of this study was to evaluate the occurrence of Shiga toxin (stx)-producing Escherichia coli (STEC) in diarrheic newborn calves, as well as the resistance profile of this microorganism against antimicrobials routinely used in veterinary therapy. The antimicrobial profile of Eugenia uniflora against E. coli clinical isolates was also analyzed. Specimens from the recto-anal junction mucosa were investigated by using chromogenic medium and identification of E. coli was done using microbiological methods (Gram staining, indole test, methyl red test, Voges-Proskauer test, citrate test, urease test, and hydrogen sulfide test). The stx1 and stx2 genes corresponding to the STEC pathotype were evaluated by using polymerase chain reaction and electrophoresis. The susceptibility profile to antimicrobial agents commonly used in veterinary therapeutic practice and the antimicrobial effect of lyophilized hydroalcoholic extract of E. uniflora L. leaves against E. coli clinical isolates were evaluated by disk diffusion and microdilution methods. Shiga toxin-positive E. coli was identified in 45% of diarrheic newborn calves (stx1 = 23.2%, stx2 = 4.0%, stx1 + stx2 = 18.2%). The frequency of stx-positive E. coli in the bacterial population was equal to 17.0% (168/990 clinical isolates): 97 (9.8%) stx1-positive E. coli, 12 (1.2%) stx2-positive E. coli, and 59 (6.0%) stx1 + stx2-positive E. coli isolates. All stx-positive E. coli analyzed showed resistance to multiple drugs, that is, from 4 to 10 antimicrobials per clinical isolate (streptomycin, tetracycline, cephalothin, ampicillin, sulfamethoxazole + trimethoprim, nitrofurantoin and nalidixic acid, ciprofloxacin, gentamicin, and chloramphenicol). Effective management measures should be implemented, including clinical and laboratory monitoring, in order to promote animal and worker health and welfare, prevent and control the spread of diseases, and ensure effective treatment of infectious diseases. The E. uniflora L. leaves showed inhibition of microbial growth based on the diameter of halos, ranging from 7.9 to 8.0 mm and 9.9 to 10.1 mm for concentrations of 50 and 150 mg/mL, respectively. This plant displayed bacteriostatic action and a minimum inhibitory concentration of 12.5 mg/mL for all clinical isolates. Its clinical or synergistic effects with antimicrobial agents must be determined from clinical and preclinical trials.

OBJECTIVE To monitor concentrations of sulfadimidine in the paranasal sinus mucosa (PSM) of unsedated horses following IV administration of trimethoprim-sulfadimidine via in vivo microdialysis. ANIMALS 10 healthy adult horses. PROCEDURES Concentric microdialysis probes were implanted into the subepithelial layers of the frontal sinus mucosa of standing sedated horses. Four hours after implantation, trimethoprim-sulfadimidine (30 mg/kg) was administered IV every 24 hours for 2 days; dialysate and plasma samples were collected at intervals during that 48-hour period and analyzed for concentrations of sulfadimidine. The dialysate concentration and relative loss of sulfadimidine from the perfusate were used to calculate the PSM concentration. RESULTS Microdialysis probe implantation and subsequent in vivo microdialysis were successfully performed for all 10 horses. Following the first and second administration of trimethoprim-sulfadimidine, mean ± SD peak concentrations of sulfadimidine were 55.3 ± 10.3 μg/mL and 51.5 ± 8.7 μg/mL, respectively, in plasma and 9.6 ± 4.5 μg/mL and 7.0 ± 3.3 μg/mL, respectively, in the PSM. Peak sulfadimidine concentrations in the PSM were detected at 5.9 ± 2.7 hours and 5.4 ± 2.3 hours following the first and second drug administrations, respectively. For 12 hours, mean PSM sulfadimidine concentration remained greater than the minimum inhibitory concentration indicative of sulfonamide susceptibility of equine bacterial isolates (4.75 μg/mL). CONCLUSIONS AND CLINICAL RELEVANCE In vivo microdialysis for continuous monitoring of PSM sulfadimidine concentrations in unsedated horses was feasible. Intravenous administration of trimethoprim (5 mg/kg) and sulfadimidine (25 mg/kg) proved likely to be efficient for treating sinusitis caused by highly susceptible pathogens, providing that the dosing interval is 12 hours.

Three hundred milk product samples were collected from different locations of Basrah province. By using enrichment broth technique and Brucella selective medium nine isolates (8 from soft cheese and one from cream) where isolated. No Brucella strain was isolated from ice-cream. The species and biotypes of these isolates were determined and it was found that 4 isolates of Brucella abortus biotype 4 and 5 isolates of B. melitensis biotype 2. Antibiotic sensitivity test showed that all isolates were sensitive to streptomycin, gentamycin, kanamycin, rifampicin, trimethoprim, trimethoprim with sulfamethoxazole and tetracycline, some strains showed resistance to doxycyclin, cephalexin, ampicillin and erythromycin. Brucella isolates also showed growth in different range of temperature and pH.

Some pharmacokinetic aspects of sulphadoxine alone and sulphadoxine-trimethoprim (TMP) combination were studied in goats following single intravenous (i.v) and intramuscular (i.m) administration of 15 mg kg–1 b.wt. After i.v injection the serum sulphadoxine concentration time course was best described by two compartment-open model with distribution half-lives (t0.5(.)) 2.48 and 2.31 h., elimination (t0.5(3)) half-lives 23.10 and 24.75 h., total body clearance (ClB) 0.076 and 0.073 L kg-1 h.-1 and steady state volume of distribution (Vdss) 368.54 and 411.73 ml kg-1 for sulphadoxine alone and sulphadoxine-trimethoprim combination, respectively. After i.m administration the mean peak serum concentrations (Cmax) 25.69 and 33.31 ug ml–1 were achieved after maximum time (tmax) of 3.09 and 2.79 h. for sulphadoxine alone and sulphadoxinetrimethoprim combination, respectively. The absorption half-lives (t0.5(ab)) were 0.58 and 0.42 h., respectively. It is concluded that a combination of sulphadoxine and TMP can provide a synergistic level for both antimicrobials and thus be a useful combination in the treatment of various goat diseases.